Operating mechanism for motor-rheostats.



No. 700,7!5. Patented May 20, I902.

'. .LJ. AYER.

OPERATING MECHANISM FOR MOTOR RHEOSTATS.

. (Application filed Feb. 1'7, 1902.) (No Model.) 2 Sheets-Sheet l.

#Q/(Qi/ 586: h I evc/( 7. 7 -444 "5M 71. 95770561 @87 fl w) XM- M No.700,7I5. Patented May 20, I902.

J. I. AYEB.

OPERATING MECHANISM FOR MOTOR BHEDSTATS.

(Application filed Fab. 17, 1902. (No Model.) 2 $haats-Sheet 2.

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UNITED STATES PATENT OFFICE.

JAMES I. AYER, OF MALDEN, MASSACHUSETTS, ASSIGNOR TO THE SIMPLEXELECTRICAL COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OFMASSACHUSETTS.

OPERATING MECHANISM FOR MOTOR-RHEOSTATS.

SPECIFICATION forming part of Letters Patent No. 700,715, dated May 20,1902. Application filed February 1'7, 1902. Serial No. 941351. (Nomodel.)

To all whom it may concern:

Be it known that I, JAMES I. AYER, a citizen of the United States,residing at Malden, county of Middlesex, State of Massachusetts,

have invented an Improvement in Operating Mechanism for Motor-Rheostats,of which the following description, in connection with the accompanyingdrawings, is a specification, like letters on the drawings representinglike to parts.

My invention is an operating mechanism for motor-rheostats, and has forits object the provision of special means for insuring that the armatureresistance of a rheostat shall be cut out before the field resistance ofthe rheostat is cut in, or, in other words, that the armature-controlarm shall be shifted before the field-control arm is shifted in startingand controlling a motor. Preferably, also, in

2b connection therewith I provide means for insuring that the fieldresistance is cut out before the armature resistance has been cut out instarting or stopping the motor. Also the more complete embodiment of myinven- 2 5 tion preferably includes the mounting of the field-controlarm and the armature-control arm together, so that they are mutuallydependent.

The constructional details and further advantages of my invention willbe more fully pointed out in the course of the following description,reference being had to the accompanying drawings, in which I haveillustrated preferredembodiments thereof, and the in- 3 5 vention willbe more particularly defined in the appended claims.

In the drawings, Figures 1 and 3 show different forms of my invention infront elevation. Figs. 2 and i are diagrammatic views thereof,illustrating the wiring; and Fig. 5 is a side elevation of portions ofFig. 3.

On a suitable insulating-base a is mounted ausual rheostat-head,consisting of usual contacts a and contact-bar b, the former being 5connected by resistances a and at its right hand end, as herein shown,being connected by a wire a to the armature a and thence by wire a toone of the line-Wires a and the latter being connected by a wire a tothe shunt-field a which is connected to the line- I wire a, anelectromagnet a being interposed in said wire a for electricallyretaining the armature a of a magnet-arm a yieldingly mounted on thesame stud (r as the armaturecontrol arm a.

The two arms a a are normally held under tension when in the positionshown in Fig. 3 by means of springs s 5', attached at one end to saidarms, respectively, and at the other end secured by suitable means, asin a slot 5 to the hub when the device is used as a motor-startingrheostat only; but when used for motor-controlling rheostat the arm a isalone held under the control of a spring 3.

he mechanism thus far described is such 63? as is commonly employed andmay be widely varied so far as concerns my invention, the purpose ofsaid mechanism being to provide means for insuring that when thefield-circuit is interrupted or when an overload 00- 7o curs the arm cawill be automatically shifted to its i off position by the release ofthe arm c which during proper operation is retained magnetically by theelectromagnet a", and the further purpose of my invention being toprovide in connection therewith means dependent thereon for controllingthe field resistance.

Referring first to Figs. 1 and 2, which show my invention in its simplerform for light work, it will be seen that I have mounted at b on the arma a field-control arm b provided with an operating-handle b for swingingits free end into successive engagement with field-resistance contactsI), whose resistances connect with the contact-bar b of the shuntfield-circuit, and, as herein shown, the circuit is completed from theline-wire a by the arm a and the arm 11 which are themselves conductorsor provided with con- 0 ductors.

In operation it will be evident that when current ceases in the field orother disturbance arises which renders the electromagnet a inoperativethe arm a will instantly be 5 thrown over to the left by its spring 5first striking the arm b and thereby shifting the latter to the left,cutting out the field resistance, and then shifting both of the arms band a over to the off position or contact a Then in this position,'it isimpossible to introduce the field resistance, because the motion of thearm 6 is limited, in the first place, by a stop or other means 19 and,in the next place, itis so mounted and of such length that it isimpossible for it to make contact with the resistance-contacts 1) untilthe armature-control arm has been shifted to the extreme right.

It will be understood that the mechanism just described is merelyoneform or embodiment of my invention, although because of itssimplicityitis a desirable form. In Figs. 3 to 5, however, I have shownanother embodiment of my invention, which for heavy work has itsadvantages over the mechanism just explained. Referring to said figures,it will be seen that I have not used the arms as conductors, but haveprovided a contact-bar I), connected by a wire 6 to the line conductor(1 and a contact-bar a connected by a wire a also to said line-wire.

It will be understood that I have omitted various constructional detailswhich are com monly found in devices of this general nature and haveconfined myself as much as possible to those features necessary to theclear description and understanding of my invention.

The field-control arm is indicated at b and is preferably pivoted on thestud a, swinging freely independently of the two arms (r a, which, asalready described, are both spring-controlled when used solely as astart in g-rheostat, in which case the arm a is also provided withlocking means, herein shown as comprising a notched plate a and a latchor dog a mounted in ears a on the base a and normally held downward by aspring (L22.

The arm 6 is locked in engagement with the arm a at all times, exceptingwhen the latter is in its extreme right position, when it isautomatically unlocked,- any convenient form of mechanism beingemployed, that herein shown comprising a pin c4 vertically movable inthe arm a and normally held downward by a spring (W, said pin carryingat its upper end an arm a, provided at its free end with a detent 64 toengage a hole or notch a in the arm 11 being released therefrom byengagement with an inclined plate a, mounted on the base Ct in positionto release said parts only when the arm a has reached the last contact aat the right.

The locking device a of the armature-control arm a extends into the pathof the magnet-arm so that when the latter flies upwardly it first shiftsthe arm b to the left, so as to remove it from the field-resistancecontacts, and in passing it releases the locking device a from thenotched plate a of the arm a, thereby permitting all three arms to moveinstantly to the left into off position, the arm I) being meanwhilelocked against the arm a by the locking mechanism carried thereby. Upondesiring to start up the motor again the operator first moves the lever(L to the right into contact with the electromagnet a" and then movesthe arm a to the right, holding the arm a in position until the arm areaches the first contact a, after which the arm a is held magneticallyby the current passing through the magnet-circuit. When the arm a hasbeen moved to the extreme right, the arm 19 (in the construction shownin Fig. 1) or the arm 11 (in the construction shown in Fig. 3) can be atonce shifted over the field-resistance contacts as may be desired, thearm a in tho construction shown in Fig. 3 being locked in its righthandposition automatically by the dog a and the arm 11 simultaneouslyunlocked by the pin (1, and plate a.

In both forms of my invention it will be seen that mechanism is providedwhich makes it impossible to introduce field resistance into the shuntfield-circuit excepting when the motor has been properly controlled orstarted by the cutting out of armature resistance.

As herein shown, the field-control mechanism cannot be made operativeuntil the armature-control mechanism has arrived at its short-circuitposition, (as it is commonly termed when the external resistance hasbeen cut out of the circuit.)

As already intimated, I do not limit my invention to the constructionaldetails herein shown and explained, as the invention in its broaderaspects is capable of a variety of embodiments, and accordingly I do notintend to limit this invention otherwise than as hereinafter expressedin the claims.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is'- 1. In a device of the kind described,armature-control mechanism, field control mechanism, means for lockingsaid armature-control mechanism in short-circuit position,- and meanspreventing the operation of said fieldeontrol mechanism until thearmature-control mechanism has arrived at said short-circuit position.

2. In a device of the kind described, a rheostat, comprising afield-control lever and re sistances therefor, an armature-control leverand resistances thereof, and means for positively moving the field-leverback to neutral position when the armature-lever is moved back toneutral position.

3. In a device of the kind described, armature-control mechanism,field-control mechanism, the latter requiring movement independent ofthe former for placing it in operative position, and a locking devicefor looking the said two mechanisms together until the armaturecontrolmechanism has been moved to short-circuit position.

I. In a device of the kind described, armature-control mechanism,field-control mechanism, the latter requiring movement independent ofthe former for placing it in operative position, a lockin g device forlocking said two mechanisms together until the armature- IIO controlmechanism has been moved to short- 1 circuit position, and means forthen autom atically unlocking said two mechanisms to permit saidindependent movement of said fieldcontrol mechanism.

5. In a device of the kind described, armature-control mechanism,field-control mechanism, means for locking said armature-controlmechanism in short-circuit position, said field-control mechanism beingoperable independently of said armature-control mechanism when thelatter is locked, and means controlled by the motor-circuit forautomatically shifting said field-control mechanism and unlocking saidlook upon interruption of said motor-circuit.

6. In a device of the kind described, fieldcontrol mechanism including alever and a series of resistances, armature-control mechanism includinga lever and a series of resistances, and means under the electricalcontrol of the motor-circuit for automatically shifting said field-leverto cut out the field resistances before movement of the armaturelever.

7. In a device of the kind described, fieldcontrol mechanism including alever and a series of resistances, armature-control mechanism includinga lever and a series of resistances, means under the electrical controlof the motor-circuit for automatically shifting said field-lever to cutout the field resistances before the movement of the armature lever, andmeans cooperating therewith for withdrawing the field-lever and puttingit into inoperative condition until the armatu relever has been put inshort-circuit position for again starting the motor.

8. In a device of the kind described, a rheostat including fieldresistances, armature resistances, and independently-movable leverstherefor, means for locking said two levers together excepting when thearmature-lever is in its short-circuit position, and means forautomatically unlocking said levers when the armature-lever is moved toits short-circuit position.

9. In a device of the kind described, an armature-control lever,resistances therefor, a spring-actuated device held under tension by thepassage of current in the motor-circuit, a field-control lever, andresistances therefor included in a shunt field-winding, saidfieldcontrol lever being located between said ar-- mature-control leverand said spring device, interruption of the retaining current of saidspring-actuated device permitting the latter to shift said field-controllever for cutting out the field resistance before movement of thearmature-control lever.

10. In a device of the kind described, resistance in a shuntfield-winding, armature resistances, independent levers thereforcoaxially mounted, and automatic means for shifting said levers, saidshifting means engaging and shifting the field-control lever for cuttingout its resistances, before engaging and operating the armature-controllever.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

J AS. I. AYER.

Witnesses:

DORA A. PROOTOR, ELIZABETH M. CoNLrN.

